stream_identity.hpp

// vim: set tabstop=2:softtabstop=2:shiftwidth=2:expandtab

#ifndef LIN_GENERATORS_STREAM_IDENTITY_HPP_
#define LIN_GENERATORS_STREAM_IDENTITY_HPP_

#include "../core.hpp"

namespace lin {
namespace internal {

template <typename T, size_t R, size_t C, size_t MR, size_t MC>
class StreamIdentity : public Stream<StreamIdentity<T, R, C, MR, MC>>,
    public Dimensions<StreamIdentity<T, R, C, MR, MC>> {
  static_assert(is_square<StreamIdentity<T, R, C, MR, MC>>::value,
      "StreamIdentity<...> must have square traits");

 public:
  typedef traits<StreamIdentity<T, R, C, MR, MC>> Traits;

 protected:
  using Stream<StreamIdentity<T, R, C, MR, MC>>::derived;
  using Dimensions<StreamIdentity<T, R, C, MR, MC>>::resize;

 public:
  using Stream<StreamIdentity<T, R, C, MR, MC>>::size;
  using Stream<StreamIdentity<T, R, C, MR, MC>>::eval;
  using Dimensions<StreamIdentity<T, R, C, MR, MC>>::rows;
  using Dimensions<StreamIdentity<T, R, C, MR, MC>>::cols;

  constexpr StreamIdentity() = delete;
  constexpr StreamIdentity(StreamIdentity<T, R, C, MR, MC> const &) = default;
  constexpr StreamIdentity(StreamIdentity<T, R, C, MR, MC> &&) = default;
  constexpr StreamIdentity<T, R, C, MR, MC> &operator=(StreamIdentity<T, R, C, MR, MC> const &) = default;
  constexpr StreamIdentity<T, R, C, MR, MC> &operator=(StreamIdentity<T, R, C, MR, MC> &&) = default;

  constexpr StreamIdentity(size_t r, size_t c) {
    LIN_ASSERT(r == c);

    resize(r, c);
  }

  constexpr typename Traits::elem_t operator()(size_t i, size_t j) const {
    LIN_ASSERT(0 <= i && i <= rows());
    LIN_ASSERT(0 <= j && j <= cols());

    return typename Traits::elem_t(i == j);
  }

  constexpr typename Traits::elem_t operator()(size_t i) const {
    LIN_ASSERT(0 <= i && i <= size());

    return (*this)(i / cols(), i % cols());
  }
};

template <typename T, size_t R, size_t C, size_t MR, size_t MC>
struct _elem<StreamIdentity<T, R, C, MR, MC>> {
  typedef T type;
};

template <typename T, size_t R, size_t C, size_t MR, size_t MC>
struct _dims<StreamIdentity<T, R, C, MR, MC>> {
  static constexpr size_t rows = R;
  static constexpr size_t cols = C;
  static constexpr size_t max_rows = MR;
  static constexpr size_t max_cols = MC;
};
}  // namespace internal
}  // namespace lin

#endif